[GHC] #14826: Flatten data types extending other data types in STG

[GHC]

#14826: Flatten data types extending other data types in STG
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        Reporter:  nomeata           |                Owner:  (none)
            Type:  feature request   |               Status:  new
        Priority:  low               |            Milestone:
       Component:  Compiler          |              Version:  8.5
      Resolution:                    |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  None/Unknown      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
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Comment (by sgraf):

 As I understand your proposal, this will re-use info pointers. Is that
 right? If so, is that a requirement?

 I imagine we could encode something more general by lifting any data
 constructor consisting purely of an unboxed sum of arity n to n distinct
 constructor tags. That way, we can drop the 'only once' requirement.

 Well, I guess this still involves non-`id` coercions... Still, we could
 encode the 'only once' thing, where we re-use constructor tags, as a
 special case to get erasable coercions.

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14826#comment:2>
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